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Dodge Repair/AC: R-134 in a R-12 system?


QUESTION: I have a dodge Ram 1500/V6. The AC does not work. Under the hood the AC lines are cold. The climate control does not work properly. If I start from the blue side with the control selector on Max/AC, only normal air blows out.If I move the climate control selector to the right there is no variation in temperature until it is almost all the way to the right in the red zone. At this point I can hear a door opening or shutting, and hot air blows out. If I move the selector to the left into the blue zone there is no change in temperature. If I turn the Max/AC off and then back on normal air begins to blow again but no cold AC air. I'm going to let my mechanic work on it, but would like to have some idea before I take it in.

ANSWER: Hi Curtis,
Are you sure the compressor is being actuated via its electro-mechanical clutch...does the engine idle speed drop a bit when you ask for AC which is normal when the clutch is actuated?
Have a helper ask for AC while you watch/listen for the compressor to start rotating.
If the AC compressor is working then either there is a problem with the expansion valve not being open inside the ac/heat box or there is a problem with temp door not sending the air over the cold coils in the box.
If the compressor is not actuating, then you may simply be low on refrigerant in the system.

What is the year model of the vehicle? It would probably be a better bet to go to an independent AC shop unless your mechanic is well-versed in AC.
PS Please 'rate/nominate' my answer/me (see the PS below).

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QUESTION: The Year model is 2001. The engine idle speed does drop a bit when the AC is turned on. The compressor actuates at 1.5 seconds engaged and 6.5 seconds not engaged. My mechanic and the man at the auto parts store said it does this when it's low on refrigerant. Would it be cost efficient to put in refrigerant then go from there.

  Thank you for your help, it is greatly appreciated.

ANSWER: Hi Curtis,
Yes, I would begin by adding a can of refrigerant. You can buy that and an adapter to install it yourself to save on labor if you are so inclined. Thanks for the rating and nomination which you can do again if you would be so kind.

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QUESTION: IF I could be a bother to ask you one more question. The advice you gave me worked out perfectly. During the process of putting in the refrigerant into the AC system of the dodge truck I notice on the can that it is to be used in the model years after 1994.

  I put R-134A refrigerant in a 1994 Chevy Cavalier. The AC ran cold for about a week then began to blow normal air. I've sinced learned that 1994 and older cars have to be retro fitted to handle the R-134A refrigerant. What damage have I done to the AC system, can it be fixed, and is it expensive.

Hi Curtis,
Two points to note: I believe the problem is definitely an issue if you put R-12 in an R-134a system. It is likely the same issue in the opposite substitution.
However, I would question whether a '94 Chevy system is designed for R-12. The manuals I have for Chrysler cars and minivans says that the R-134a systems began with the '93 model year. And  besides the fittings for inserting the two types of refrigerant are purposely different so as to reduce the likelihood of the error from ever occurring. Verify with an AC shop if both those points are indeed correct.
So my belief is that you used the correct refrigerant BUT you either didn't use enough or that you have a leak in the system.
Thanks for your earlier rating and nomination. You can do both again if you would be so kind.

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Roland Finston


Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

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